I think, as seems standard, Bking is talking twaddle.
If he’d made a more general point that the extent, and level, of man’s efforts into space are greatly exaggerated, I might be inclined to agree.
I was hoping he’d come back. I haven’t seen this much back tracking since the PS3 launched and I was still posting on video game forums.
sonflowerinwales:
Evening folks
Our GPS satellite transmit signals at around 60w. That gets through clouds, smog and all the other nasties in our climate.
Cheers
Paul
Not convinced its strong enough to get past the Valley Commandos though… 
raymundo:
Bluey Circles:
raymundo:
Marine and aviation sat navs work better than your car or truck sat nav because they have to be constructed to more stringent regulations before they are passed for use, they can also one be a hell of a lot more expensive.If you are ■■■■■■■ in harbour for a few days, does your GPS position vary at all, and if they have bizarrely included altitude in the display is it accurate enough to show you if the tide is in or out. and and and is ‘sea level’ when the tide is in or out or halfway, is it something to do with Liverpool.
I am sad enough to have already worked the following out, and my satnav can have my house moving by up to about 20m from side to side and about 20m up and down.
It depends on how the filter is set, if the filter is set for say 1 second then yes it does fluctuate slightly but have the filter set to every five seconds then no. The filter is what decides the displayed position, basically averaging out the info received over a longer period of time depending on the vessels speed over the ground.(faster you go the less time in the filter, slower then more) One of our GPS does show altitude but I turned that facility off whereas the others don’t.
I was really meaning does the position on your GPS change over many hours even though your ship has been entirely stationary. For instance; Since my earlier post (may be 7 hours ago) my house according to my GPS has drifted 4 meters to the SW. My house seems to have a drift range of up to 15m from its true position - sadly it never goes any further, I look out of the window every morning in hope that I can see some caribean palm trees.
Well he has been back on since…
Last visited:Wed May 18, 2016 11:51 pm
So why no signal when your at sea or on a plane.
If the “satellites” are “transmitting” straight to your phone or whatever why no signal at sea?
How come these “satellites” never need maintenance,how come they never get struck by micro meteors,how come their batteries never fail(and before you give me some crap about solar panels if they are in geosynchronous orbit they must be in the dark half the time)How do they put them in orbit,these things dont have engines and the “shuttle” only goes up to 400 miles,How do they maintain a none decaying orbit without engines not just over weeks but 20 years.Why does your phone have to be within 10 km of a cell mast to have an operational signal yet these little “wonders” can transmit over thousands of kilometers at less than one kilowatt to the same device.Cell masts transmit at 100 times this power(look at the cables that power them)yet only have a range of 10km.Why would the American military provide all this for "free."Why is their no “sat nav” signal in the Sahara,Gobi or Atacama deserts.Why can you have 2 different devices in the same truck giving different speeds if they are “accurate” to 1 meter.Both working off the same satellites or maybe different cell net providers towers?Why does Google earth turn into a CGI image above a set height.If its a view from a “satellite” why cant it be a picture.
raymundo:
Bking, you do talk such a load of ■■■■■■■■.
I have been using electronic navigation charts linked to a GPS receiver at sea for the last 20 years or so and have always got to my destination safely and knew where I was to a metre or two. The technology employed to determine speed, location and altitudes is so far advanced now it far beats a tacho by miles.
How? A reflective sticker is put on a tyre,this is read by a laser,the wheels are on rollers of a set diameter.The wheels turn the rollers which gives a set distance,the laser counts out a precise number of turns of the wheel.Now I know arithmetic might not be your strong point but if you divide the number of rotations of the wheel into the distance the rollers have turned ( it may appear to be magic )you arrive at a K factor.This tells you that a certain number of rotations of that wheel in a set time interval will produce a speed of X kph.
So if the wheels circumference is say 2 meters and it rotates 5 times per second then in one hour it will cover 36 km get it?
Now this is a physical fact measured on a 50 grand machine but of course your £49.99 “sat nav” is far more accurate isnt it cos the pixies tell you so.
He’s using his GPS and saTnav to find those old brake chambers.
hold a tablet with satnav on upto window of aircraft and it will pick up your location , providing the map of country is in map folder. done that a few times over Europe.
Bking:
So why no signal when your at sea or on a plane.
If the “satellites” are “transmitting” straight to your phone or whatever why no signal at sea?
You will have a GPS signal when at sea or in the air. What you won’t have is things like the map information stored on your device. (I’m assuming you mean a mobile as you keep referring to cell towers) the only reason you’d need cell towers for the GPS is because they’re providing the mapping information to your device.
If GPS technology is so inaccurate then how come missiles can be fired and have such accuracy when hitting a target?
gezt:
hold a tablet with satnav on upto window of aircraft and it will pick up your location , providing the map of country is in map folder. done that a few times over Europe.
Which road your flying over.Does it tell you to turn left at the next roundabout?
So how come you dont get latitude and longtitude co ordinates on a ship.
Maybe because the aircraft is 5 miles nearer to these little “wonders”
Roymondo:
GPS works perfectly at sea and in aircraft (better than on dry land, because there are no mountains, valleys or buildings to block or reflect the signals). The reason it doesn’t appear to work on a ferry etc is because all that metal superstructure blocks the (very weak) radio signals from reaching inside the vessel.[/quotHow the hell do you block a signal from"space" with a mountain,valley or building?
Unless you got a 22000 km high block of flats in your area!!!
m1cks:
Bking:
So why no signal when your at sea or on a plane.
If the “satellites” are “transmitting” straight to your phone or whatever why no signal at sea?You will have a GPS signal when at sea or in the air. What you won’t have is things like the map information stored on your device. (I’m assuming you mean a mobile as you keep referring to cell towers) the only reason you’d need cell towers for the GPS is because they’re providing the mapping information to your device.
If GPS technology is so inaccurate then how come missiles can be fired and have such accuracy when hitting a target?
Like the “smart bombs” the filth used in Iraq which were “GPS” guided?
Shame less than 2% came within 500 meters of their target and blew a kid and his mother to bits instead.A bargain at 500,000 dollars a “pop”.
I agree satnav speed is completely accurate. Except for one slightly troubling thing. I’ve got a tomtom and a nextbase dashcam. The dashcam shows a sort of compass and speedo once it’s got a signal and it shows a different speed to the tomtom. It’s usually about 1 mph slower but sometimes 3 or more.
Course satnav must show an inaccurate speed when you are going up or down hill as you are not travelling in a straight line.
Bking:
How the hell do you block a signal from"space" with a mountain,valley or building?
Unless you got a 22000 km high block of flats in your area!!!
This thread is going to be very educational for you.
To answer your question I would suggest research into line of sight in relation to GPS signals, triangulation and how the earth is believed not to be flat.
Buy a man a fish and he will eat for a day buy him a fishing rod and he will probably sell it and buy a fish.
Bking:
So why no signal when your at sea or on a plane.
If the “satellites” are “transmitting” straight to your phone or whatever why no signal at sea?
Somebody who pilots a ship has already told you that there is a signal at sea.
Bking:
How? A reflective sticker is put on a tyre,this is read by a laser,the wheels are on rollers of a set diameter.The wheels turn the rollers which gives a set distance,the laser counts out a precise number of turns of the wheel.Now I know arithmetic might not be your strong point but if you divide the number of rotations of the wheel into the distance the rollers have turned ( it may appear to be magic )you arrive at a K factor.This tells you that a certain number of rotations of that wheel in a set time interval will produce a speed of X kph.
So if the wheels circumference is say 2 meters and it rotates 5 times per second then in one hour it will cover 36 km get it?
Now this is a physical fact measured on a 50 grand machine but of course your £49.99 “sat nav” is far more accurate isnt it cos the pixies tell you so.
Sounds straight forward but it isn’t just that simple, aggravating factors such as tyre pressure and load on the tyre can make that diameter smaller, and then further confusion when the centrifugal forces at speed try to make the diameter bigger.
Before the electronic wizardry of GPS , speed tests were done with a bicycle wheel mounted on a frame at the rear of a vehicle, this way the inaccuracies of the larger tyre could be ruled out.
Eric Rambler:
Course satnav must show an inaccurate speed when you are going up or down hill as you are not travelling in a straight line.
at max gradient on a motorway 1:25 the error caused by the incline will be around 0.08%, so a true 56 may read at 56.04, so not worth bothering about.
To come back to the original point, I find that some trucks consistently give a higher speed reading on the speedo and the tacho than my sat-nav does, whatever the gradient. It’s typically 3mph out at top speed, so it’ll think it’s doing 56mph when it’s really doing 53. Scanias are the worst offenders, and when I mentioned this to a Scania repair man he said my sat-nav was wrong. Are they deliberately calibrating them 3mph out so that they get more accurate as the tyres wear? The problem is absent or much less pronounced on other makes of truck (including MAN).
Sent from my iPhone using Tapatalk
Harry Monk:
Bking:
So why no signal when your at sea or on a plane.
If the “satellites” are “transmitting” straight to your phone or whatever why no signal at sea?Somebody who pilots a ship has already told you that there is a signal at sea.
*pedant mode on *
Unless Raymundo is a Pilot, and guides a ship in or out of a harbour or across a dangerous transit, he is not really piloting the ship.
pedant mode off
raymundo:
098Joe:
Apparently sat navs can only give accurate speed on level ground (ie the device is moving in two dimensions at the same time if going up or down a hill). I am sure somebody will say I am talking [zb] thoughHave to be me then
How do you think aeroplanes manage then ?
It’s all down to triangulation and similar stuff.
I thought the subject was accurate speed measurement, not how aeroplanes find their way around? Do you know for sure that I am wrong?